1. Field of the Invention
The present invention relates to a pitching control system for a skid steer vehicle, for suppressing the pitching motion of the skid steer vehicle liable to occur during turning and straight running.
2. Description of the Related Art
The skid steer vehicle is turned by a differential rotation of the right and left driving wheels thereof. During a skid-turn, the driving wheels of the skid steer vehicle skid, and consequently, the tires are deformed and produce a stick-slip motion, and the body jolts in a so-called pitching motion. The jolting movement of the body makes it difficult for the operator to properly control the control levers, and consequently, the pitching motion of the skid steer vehicle continues and the degree of pitching motion is increased.
The skid steer vehicle, in general, has a small wheel base for high turning performance, and hence the skid steer vehicle is liable to pitch even during straight running. As is generally known, the closer the weight distribution ratio to one, the greater the degree of pitching motion. Accordingly, it is a conventional practice in designing the geometry of the skid steer vehicle to improve the turning performance by increasing the unladen distributed weight on the rear wheels, but this makes reverse running unsafe. Furthermore, even if the gravitational center of the skid steer vehicle in the unladen state is biased toward the rear of the vehicle, this gravitational center shifts toward the front when the skid steer vehicle is laden, and therefore the laden weight distribution ratio approaches 1.0, and thus the degree of pitching motion is increased.
The pitching motion of the skid steer vehicle which occurs during turning and straight running not only makes the operator uncomfortable and unsteady, but may cause the skid steer vehicle to turn over. Accordingly, the pitching motion of the skid steer vehicle must be suppressed for safe running.